蛋白质琥珀酰化是一种新的翻译后修饰类型，但目前人们对这种修饰的作用底物、生理病理功能和调控机制知之甚少。最近发现定位于线粒体的蛋白SIRT5是一种调节蛋白去琥珀酰化的催化酶。我们发现SIRT5在肝癌中显著下调表达，SIRT5敲除小鼠胚胎成纤维细胞出现了糖酵解作用增强，线粒体内活性氧水平上升等肿瘤细胞代谢特征,提示SIRT5很可能是一个肿瘤抑制基因。为了研究SIRT5抑癌的分子机制，我们从鉴定其底物入手，用蛋白质组学技术鉴定了线粒体蛋白的上百个可能受SIRT5调节的赖氨酸琥珀酰化位点。本研究以其中一个潜在底物-超氧化物歧化酶MnSOD为对象，探讨SIRT5介导的去琥珀酰化对MnSOD酶活性的影响和在细胞氧化应激调控的作用,力图阐明SIRT5发挥抑癌作用的其中一条分子路径。将在分子、细胞和肿瘤病理学等多层面探讨SIRT5、蛋白质琥珀酰化和氧化应激调控这三者的相互关系及其在肿瘤发生发展过程中意义

Lysine succinylation is a new post-translational modification and it has been recently demonstrated that mitochondrial localized SIRT5 serves as a key enzyme for removing succinyl groups from lysine residues, but the substrate proteins, the biological significance, and the regulatory mechanism of protein succinylation remains to be determined. . The hypothesis that SIRT5 serves as a tumor suppressor in vivo was supported by our preliminary results that SIRT5 expression is decreased in liver cancer as compared with normal liver tissue samples. In addition, the SIRT3-/- MEFs exhibited higher levels of total cellular superoxide as well as mitochondrial superoxide levels when compared with the SIRT5+/+ MEFs. Furthermore, SIRT5 knockout cells consume increased amounts of glucose. It looks like the SIRT5 knockout cells acquire some characteristics of tumor cells.. In order to determine the molecular mechanism of SIRT5 as a tumor suppressor, proteomics survey was utilized to identify substrates of the desuccinylase SIRT5. Notably, hundreds of mitochondrial proteins were identified as succinylated and potentially modified by SIRT5. We have found that many metabolic enzymes are succinylated. In particular, an important antioxidant enzyme - mitochondria manganese superoxide dismutase (MnSOD) - is a potential target of SIRT5. . We propose that SIRT5 desuccinylates and regulates MnSOD to scavenge ROS, which could be one of the key mechanisms for SIRT5 as a tumor suppressor. Here we will utilize complementary cell biology, molecular biology, and neoplasms / patholology approaches to investigate the role of succinylation in the regulation of MnSOD activity and in the cellular anti-oxidative response.